Band structure of TlGaSe₂

Abstract

A model of the TlGaSe,-I band structure of the monoclinic modification is proposed. The monoclinic modification of TIGaSe,-I is considered as a deformed tetragonal one. The band structure of the metastable tetragonal modification of TlGaSe,-II is calculated by the pseudopotential method. The irreducible representations of the DiZ group (TlGaSe,-11) are expanded in irreducible representations of the ( 3: group (TlGaSe,-I). It is found that the top of the valence band is located a t the point Y (0,2n/b,, 0) of the TIGaSe,-I Brillouin zone and is formed from band states N,, N,, of the tetragonal modification. The bottom of the conduction band is located a t the point I' of the TIGaSe,-I Brillouin zone and is formed from T4 states. An additional extremum of the valence and conduction bands is located a t the points I'(A,) and Y(N,, N8), respectively. An interpretation of the absorption spectra of TIGaSe,-I near the fundamental edge is proposed. npeAnomeIla MOAei JIb 30HHOB CTPYHTYPLI TIGaSe,-I MOHOKJIHHHOt MOAH@HIcaWWi. MomHnHHIIaR MOAH@HKaL[HfI TIGaSe,-I paccMoTpeHa KaIC Ae@OpMHpOBaHHaR TeTpa-rOHaJILI-IaFI. 30HHaR CTpyHTypa MeTacTa6HJrbHOl% TeTparOHaiJIbHOI% MOnH@HX3UEzH BOAHMLIX IIpencTaBJIeHHHi% rpynnLI D; : (TlGaSe,-11) I I O HeIIpHBOiTHMLIM IIpeaCTaB-JIeIlEzfIM rpyniIM c: (TIGaSe,-I). HaBAeHo, YTO JIOTOJIOH B2IJIeHTHOg 30HLI pacnoJIomeH B TOYKe Y (0, 2nlbm, 0) 30IlbI EPHJIJII03Ha TlGaSe,-I Ez 06pa30BaH 113 30HHbIX COCTORHHg N,, N4 TeTpWOHaJILHOa MOAH@HKaUHM. AH0 30HLI lIpOB0nHMOCTH paCIIOJIOmeH0 B TOYHe I? 8 O H h I EpkIJIJIIO3Ha TlGaSe,-I H 06pa30sa~o H 3 COCTOHHHH T,. ~OIlOJIHHTenbHbIs 3HCTpeMYM B&TIel-ITHOfi 30HLI JIOKaJIH30BaH B TOYHe I'(A,), a 30IlLI IIpOBOAHMOCTH B B6nH3Ez @yHnaMeIITaJIbHOrO R p a H . TlGaSe,-II paccwmar-la MeToAoM nceBAonoTeiwnana. IIponeReHo p a m o m e~~e n e n p~-Towe Y(N,, N,) . IIpeAnomeHa HwrepnpeTaUm cneKTpoB nornolueam TIGaSe,-I

Band structure of TIGaSe2 ternary layered crystals

“…The comparison of the results of the calculation by the method of pseudopotentials with those given in [9] revealed that the number of bands of a certain symmetry, the total width of the valence bands, and the qualitative picture of the band sequence are in good agreement. But, as the present calculations were made without additional approximations, we believe that they give a better illustration of the band structure of TlGaSe,.…”

Structural and electrical properties of TlGa(SxSe1−x)2 mixed crystals

“…Since the structure of A 3 B 3 C 6 layer crystals, such as TlGaSe 2 , TlGaS 2 , TlInSe 2 and TlInS 2 were generally assigned as tetragonal or monoclinic with space group C 6 2h , and its pseudotetragonality was attributed to the presence of micro twins [4,20]. It was reported that this ambiguity of this class of compounds may also be related with different possible versions of layer stacking [2].…”

Vacancy Formation Energy for the Charged and Neutral States of TlGaSe$_{2}$ Crystal

“…This, in their turn, indicates that TlGaSe 2 is an indirect gap semiconductor with the indirect gap from  to -Y line of 0.87 eV, while the direct gap at the -point is 0.99 eV. Indirect scenario of bands at the energy gap is favoured by other works, e.g., [18][19][20][21] too. However, the particular indirect schemes vary from work to work according to the earlier works [18,19]: the additional valence band maximum on Y line might be responsible for the indirect scenario.…”

“…Indirect scenario of bands at the energy gap is favoured by other works, e.g., [18][19][20][21] too. However, the particular indirect schemes vary from work to work according to the earlier works [18,19]: the additional valence band maximum on Y line might be responsible for the indirect scenario. Nevertheless, the later works [20,21] and the present calculations, which used more advanced computation techniques, commonly advocate the conduction band bottom that is not in -point.…”